Biomedical subjects

S Koizumi

Publications and source records attributed to S Koizumi.

At least 19 recordsLinked to original sources

PubMed1992

Zinc-specific activation of a HeLa cell nuclear protein which interacts with a metal responsive element of the human metallothionein-IIA gene.

Transcription of metallothionein genes is activated by heavy metals such as zinc and cadmium, and a DNA element called metal responsive element (MRE) is essential for this process. By mobility-shift assay, we identified a HeLa-cell nuclear protein which specifically binds to MREa of human metallothionein-IIA gene. This protein, named ZRF (zinc-regulatory factor), is present in the cells untreated with heavy metals. Zinc is essential for, and increases in a dose-dependent manner, the binding of ZRF to MREa. Other heavy metals which can also induce metallothioneins, including cadmium, copper and mercury, do not activate ZRF. A MREa-containing oligonucleotide that can bind ZRF confers heavy metal-inducibility to a heterologous promoter, suggesting that ZRF is a zinc-dependent transcriptional activator. In addition to the MRE core sequence, the surrounding sequences are also important for both ZRF binding in vitro, and zinc-dependent transcriptional activation in vivo. MREa by itself responds not only to zinc but also to other metallothionein-inducing heavy metals, indicating that the ZRF protein, not the MREa sequence, is responsible for the zinc specificity.

Base Sequence↗

PubMed1992

A nuclear factor that recognizes the metal-responsive elements of human metallothionein IIA gene.

Expression of metallothionein (MT) genes is regulated by heavy metals mainly at the transcriptional level, via cis-acting elements called the metal-responsive elements (MREs). A HeLa cell nuclear factor that recognizes MREs of the human MTIIA (hMTIIA) gene, MREBP, was characterized. Mobility shift assay and DNase I footprinting experiments showed that MREBP binds specifically to several MREs present upstream of the hMTIIA gene. Cadmium and zinc ions inhibited binding of MREBP to a MRE at high concentrations, suggesting a role of MREBP in the negative regulation of the hMTIIA gene. MREBP was partially purified by passing the HeLa nuclear extract over heparin-agarose, Sephacryl S-300, and MRE-Sepharose affinity columns. Blotting experiments showed that a polypeptide with an M(r) of 112,000 is responsible for the MREBP activity.

Base Sequence↗

PubMed1992

Human ETS1 oncoprotein. Purification, isoforms, -SH modification, and DNA sequence-specific binding.

The human ETS1 proto-oncogene proteins have been isolated from the T-cell leukemia line, CEM, by immunoaffinity chromatography and their identity confirmed by NH2-terminal amino acid sequencing. Incubation of CEM cells with N alpha-p-tosyl-L-lysine chloromethyl ketone (TLCK) indicates that ETS proteins can be modified in their cellular context and that pretreatment of the cells with N-ethylmaleimide (NEM) protects ETS1 proteins from TLCK modification. These data show that ETS1 proteins can exist in at least two different states, -SH-available and -SH-protected. Renatured human ETS1 has DNA sequence-specific binding to the PEA3 (CAGGAAGT) motif. The ETS1.PEA3 complex can be observed by electrophoretic mobility shift assays (EMSA). Purified ETS1 retards a band which is exactly the same size as a complex that is retarded from nuclear extracts prepared from CEM cells. Reduced ETS1 is required to form the ETS1.PEA3 complex, however; modification of the ETS1 -SH groups by either NEM or by TLCk does not inhibit formation of the complex. The ETS1.PEA3 complex formed with TLCK-modified ETS1 has a slower mobility than the complex formed with unmodified ETS1. Zone sedimentation analysis of purified ETS1 indicates that it is the monomer of ETS1 which binds to the PEA3 oligonucleotide.

Amino Acid Sequence↗

PubMed1992

Expression of myeloid cell phenotypes by a novel adult T-cell leukemia/lymphoma cell line.

BACKGROUND: Human T-cell leukemia virus type 1 (HTLV-1) can infect a number of cells of different lineages in vitro, yet the immunophenotypes of most adult T-cell leukemia/lymphomas (ATLs) are restricted to CD4+. The apparent discrepancy between these findings is still largely unknown. PURPOSE: We report on a unique case of ATL in which the leukemia cells were positive for both T-cell and myeloid cell antigens. To characterize these cells, we isolated cell lines from this patient with ATL. METHODS: The fresh leukemia cells were cultured without the addition of interleukin-2. Cell cloning was carried out by limiting dilution. RESULTS: A cell line (MU) and its clonal sublines were established. MU cells showed the same chromosomal abnormalities and T-cell receptor beta-chain gene rearrangement pattern as those of fresh leukemia cells. MU cells were exclusively positive for a myeloid cell marker (CD13) but not for T-cell markers, despite the presence of T-cell receptor gene rearrangement. CONCLUSION: The established ATL cell line showed both T-cell and myeloid cell characteristics, which seems to be the first evidence for the close association of ATL cells with both lymphoid and myeloid features. The cell line may provide a new insight for the targets of HTLV-1 infection and transformation in vivo.

Adult↗

PubMed1992

Endothelin-3 stimulates the release of catecholamine from cortical and striatal slices of the rat.

Endothelin-3 (ET-3) evoked the release of dopamine/noradrenaline from cortical slices and dopamine from striatal slices in a concentration-dependent manner. This action peaked slowly and was long-lasting in real-time monitoring, being different from the high K(+)-evoked response. The striatal response to 10 microM of ET-3 was reduced by extracellular Ca2+ depletion to 40% of control and by Ca2+ antagonists, especially nifedipine and flunarizine, to 40% of control. Our findings suggest that ET has a physiological significance in the brain as a neuromodulator for catecholaminergic transmission.

Animals↗

PubMed1992

Infection of the HTLV-I-harbouring T-lymphoblastoid line MT-2 by Epstein-Barr virus.

Epstein-Barr virus (EBV), a ubiquitous human B-lymphotropic virus, is associated with certain lymphoproliferative diseases of T-cell lineage. To understand the mechanism by which EBV infects T cells, we have tested the susceptibility of various human T-cell lines to the virus. We report here that the HTLV-I-harbouring T-lymphoblastoid line MT-2 carries a high level of CD21/EBV receptors on their surface, adsorbs fluorescein isothiocyanate-labeled EBV, and synthesizes virus latent antigens (EBNA-1 and LMP) following EBV infection. Pretreatment of MT-2 cells with anti-CD21 monoclonal antibody OKB7 inhibited the virus binding as well as the synthesis of virus latent antigen. These data suggest that human T-cells can be infected with EBV via functionally active virus receptors.

Antigens, Differentiation, B-Lymphocyte↗

PubMed1992

Architectural distortion of subcutaneous fascial layer in breast tumors: ultrasonographic evaluation.

To develop a criterion to evaluate architectural changes of the subcutaneous tissue layer around the breast, 120 patients with histologically proven tumors were studied as to ultrasonographical delineation of the superficial layer (SL) of the superficial fascia. Breast ultrasonography was performed using an electronic-linear scanner with a 5.0 MHz probe. When SL was identified over the tumor, it was classified into 3 types: flat, disrupted, and convergent types. SL was identified in 106 patients (88%). Forty-six were evaluated to be flat type, and 41 (89%) of them had benign tumors. The remaining 60 were subdivided into either disrupted (n = 44) or convergent type (n = 16); 53 (88%) of these 60 cases had cancerous lesions. Histologically, inward retraction of SL was the most common pattern in breast cancer. Thus, the ultrasonographic pattern of SL reflects the histological findings and can be a useful clue to differentiate benign lesions from cancerous ones.

Adult↗

PubMed1992

Simultaneous expression of T-cell and myeloid cell phenotypes in eight newly established HTLV-I-positive T-cell lines.

Eight cell lines were established from patients with adult T-cell leukemia, and from normal adults, by cocultivation with human T-cell leukemia virus type I(HTLV-I)-producer cell lines in the presence of interleukin-2. All of these cell lines harbored HTLV-I and showed T-cell markers CD2, CD3 and CD4, but not B-cell markers. Unexpectedly, all eight cell lines expressed a myeloid marker CD13 and three of the eight lines also expressed another myeloid marker CD33. Dual staining showed the simultaneous expression of CD3 and CD13 on the same cells. Thus, evidence was obtained for the expression of myeloid antigens on HTLV-I-harboring T cells.

Adult↗

PubMed1992

Role of peptidases in bradykinin-induced increase in vascular permeability in vivo.

The purpose of this study was to examine whether neutral endopeptidase and angiotensin I-converting enzyme, two membrane-bound metalloenzymes that are widely distributed in the microcirculation, play a role in bradykinin-induced increase in vascular permeability in the hamster cheek pouch. Changes in vascular permeability were quantified by counting the number of leaky sites and by calculating the clearance of fluorescein isothiocyanate (FITC)-dextran (molecular mass, 70,000 d) during suffusion of the cheek pouch with bradykinin. Bradykinin produced a concentration- and time-dependent increase in the number of leaky sites and clearance of FITC-dextran. The selective, active site-directed neutral endopeptidase inhibitors phosphoramidon (1.0 microM) and thiorphan (10.0 microM) and the selective angiotensin I-converting enzyme inhibitor captopril (10.0 microM) each shifted the concentration-response curve to bradykinin significantly to the left. During suffusion with bradykinin (1.0 microM) and phosphoramidon, the number of leaky sites increased significantly from 17 +/- 2 to 27 +/- 4 sites per 0.11 cm2 (mean +/- SEM, p less than 0.05), and FITC-dextran clearance increased significantly from 1.0 +/- 0.2 to 2.1 +/- 0.3 ml/sex x 10(-6).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Inhibitory effect of NMDA on dopaminergic transmission in a slice preparation of rat globus pallidus.

The effect of N-methyl-D-aspartate (NMDA) on KCl-evoked endogenous dopamine (DA) release from slices of rat globus pallidus (GP) was examined. NMDA inhibited the KCl-evoked DA release in a dose-dependent manner. This inhibition was blocked by CPP, an NMDA antagonist. Tetrodotoxin partially antagonized the effect of NMDA. The NMDA-induced inhibition was also partially antagonized by bicuculline methiodide and was mimicked by muscimol. These results strongly suggest that 1) an activation of NMDA receptors exerts an inhibitory effect on dopaminergic transmission in GP and 2) GABAergic transmission is involved in the effect of NMDA.

Animals↗

PubMed1992

Nebracetam (WEB 1881FU) prevents N-methyl-D-aspartate receptor-mediated neurotoxicity in rat striatal slices.

The effects of nebracetam were investigated on N-methyl-D-aspartate (NMDA) receptor- and voltage-operated Ca2+ channels (VOCC)-mediated neural dysfunction by directly monitoring the real-time dynamics of dopamine released from rat striatal slices. Nebracetam (10(-5) and 10(-4) M) completely protected against striatal dopaminergic impairment induced by L-glutamate and NMDA, respectively. BAY K-8644-evoked striatal dysfunction was not blocked by nebracetam (10(-4) M). Therefore, nebracetam seems to produce a neuroprotective action by interacting, at least in part, with NMDA receptor-operated Ca2+ channels.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

PubMed1992

Estimation of metallothionein synthesis in cadmium-exposed human lymphocytes by gel electrophoresis and silver staining.

Metallothionein (MT) is a low molecular weight metal-binding protein that is induced by a variety of heavy metals, and therefore is a candidate for an index in the biological monitoring of heavy metal exposure. As an approach to the establishment of a practical monitoring method, we estimated the MT levels in Cd-exposed cultures of human peripheral blood mononuclear cells as well as purified lymphocytes using a technique developed for the electrophoretic analysis of MTs. By this procedure, we could successfully detect the MTs induced by Cd in a dose-dependent manner. MTs were detectable even in cells exposed to as low as 0.5 microM Cd, which is close to the blood Cd levels of exposed workers. These results indicate the usefulness of this technique as a practical method for the monitoring of heavy metal exposure.

Cadmium↗

PubMed1992

Frequent association of Epstein-Barr virus in Japanese patients with Burkitt's lymphoma.

Seven Japanese patients with Burkitt's lymphoma (BL), residing in Hokkaido, were studied during the period, 1979-1991. Immunological analyses of their lymphoma cells showed all to express surface and/or cytoplasmic immunoglobulins. Chromosomal analysis was performed in five cases. Four of the five lymphomas had the chromosomal translocation, t(8;14), and one had t(2;8). Three patients had extremely high IgG antibody titers to Epstein-Barr virus (EBV) viral capsid antigen (VCA) and to EBV early antigens (EA). Two patients had positive antibodies to EA, and two others had normal antibody patterns comparable to those of EBV-seropositive age- and sex-matched healthy controls. Four of the seven lymphomas (57.1%) were positive for EBV-determined nuclear antigen (EBNA) by anticomplement immunofluorescence and/or EBV DNA using DNA-DNA reassociation kinetics, and/or Southern blot analysis. The frequency of EBV positivity in BL patients residing in Hokkaido was higher than that of cases previously reported in Japan. Three of the four EBV genome-positive BL patients responded well to chemotherapy, radiotherapy and/or surgical treatment, with no significant relapse being observed during the study period. In contrast, EBV genome-negative patients had poor prognoses despite having similar levels of clinical staging at the time of diagnosis.

Adolescent↗

PubMed1992

Japanese mothers' responses to the diagnosis of childhood diabetes.

Japanese mothers who had newly diagnosed diabetic children responded with shock, defensive retreat, and increased anxiety. During this process, the degree of their isolation was shown as trauma. Although many mothers had a strong reaction and suffered depression, loss of weight, pain, and feelings of exhaustion, they adapted to the diagnosis by the end of 1 year. Compared with an American study (Hamburg & Inoff, 1983), some of the mothers' patterns of coping were similar to those used by mothers in the United States; others were related specifically to accepted Japanese cultural practices. They used several characteristic coping strategies: resignation, holding out, and believing in religion. Nurses need to be aware of the fact that mothers face a variety of psychological stress factors after their children are diagnosed as diabetic. They should be encouraged to feel and express a realistic hope.

Adaptation, Psychological↗

PubMed1991

Clinical significance of CD7-positive stem cell leukemia. A distinct subtype of mixed lineage leukemia.

Ten leukemia cases with mixed phenotype were investigated in terms of clinical characteristics and cellular origin. Three patients were infants and six patients were older children. Six of them had a high leukocyte count and a mediastinal mass was found in three cases. All but one showed hepatosplenomegaly and/or lymphoadenopathy. In spite of intensive chemotherapy, most of them responded poorly. Cytochemical analysis of their leukemic cells revealed a low percentage of positivity for myeloperoxidase reactivity (less than 25%) in two cases and electron microscopic platelet peroxidase reactivity was found in one of three analyzed cases. Phenotypically, these cells all expressed CD7, and other T-lineage-associated, B-lineage-associated, and/or myeloid-associated antigens were also detected to some extent. In addition, three cases expressed CD41 and one case expressed CD56. The T-cell receptor (TCR) genes and immunoglobulin gene were in the germline configuration in seven cases. In three rearranged cases, two showed only the TCR-delta gene rearrangement, and one had both TCR-gamma and delta gene rearrangements. Cell culture studies with 12-0-tetradecanoyl-phorbol-13-acetate (TPA) revealed differentiation to the T-lineage in two cases and to a myeloid lineage in one case. Megakaryocytic differentiation was detected in two cases in culture without TPA. These results suggest that the cells from these cases arose from stem cells capable of both lymphoid and nonlymphoid differentiation. Although the cells were heterogeneous with regard to their potency of differentiation, they have similar clinical characteristics. Because of poor prognosis, it is important to identify this type of leukemia, and allogenic or autologous bone marrow transplantation should be considered.

Acute Disease↗

PubMed1991

Chromosome translocation and c-MYC activation by Epstein-Barr virus and Euphorbia tirucalli in B lymphocytes.

Dual exposure to Epstein-Barr virus and purified 4-deoxyphorbol ester derived from the plant Euphorbia tirucalli induced a high frequency of chromosomal rearrangements in human B lymphocytes in vitro. Rearrangements most commonly affected chromosome 8, the chromosome most often showing structural changes in Burkitt's lymphoma (BL) cells. E tirucalli is indigenous in parts of Africa where BL is endemic and may be an important risk factor for the disease.

B-Lymphocytes↗

PubMed1991

Differentiation of PC12 cells with K-ras: comparison with nerve growth factor.

The cell line PC12, derived from a rat pheochromocytoma, has served as a model for studies on the mechanism of action of nerve growth factor, as well as for the exploration of neuronal differentiation in general. When treated with nanomolar concentrations of nerve growth factor, these neoplastic chromaffin-like cells stop dividing and acquire, for all intents and purposes, the phenotype of mature sympathetic neurons. This phenotype is characterized by the extensive outgrowth of electrically excitable neurites, the ability to form functional synapses, and the acquisition of a number of biochemical markers. Treatment of PC12 cells with retroviral vectors encoding the K-ras, the N-ras, or the v-src oncogenes also produces a marked morphological differentiation very similar to that seen upon treatment with nerve growth factor. Treated cells stop dividing and develop an extensive network of neurites. It has recently been shown that PC12 cells differentiated with v-src, while resembling, morphologically, those treated with nerve growth factor, differ substantially in the biochemical characteristics normally associated with nerve growth factor-induced differentiation. Cells infected with K-ras also develop a neurite network similar to that seen after treatment with nerve growth factor. In addition, such cells develop tetanus toxin-binding sites and saxitoxin-binding sites, as do cells treated with nerve growth factor. Decreases in the binding of epidermal growth factor and in the activity of calpain also occur and these, as well, are characteristic of nerve growth factor-treated cells. But the adhesive properties of cells infected with K-ras are different than those of nerve growth factor-treated cells, and the former do not show an increase in the NILE glycoprotein. Finally, K-252a, an inhibitor of the actions of nerve growth factor on PC12 cells, has no effect on the neurite outgrowth produced by infection with K-ras. Thus, many of the key markers of nerve growth factor-induced differentiation of PC12 cells also appear upon differentiation with K-ras, but there are, nevertheless, some crucial differences in the properties of these two sets of cells.

Amphibian Proteins↗

PubMed1991

A nuclear factor that interacts with metal responsive elements of a human metallothionein gene.

Metallothioneins (MTs) are low molecular weight heavy metal-binding proteins which are known to play a major role in heavy metal detoxification and understanding of their regulatory mechanism is toxicologically important. Expression of MT genes is induced by heavy metals and metal responsive elements (MREs) upstream of MT genes are essential for the transcriptional activation. By several types of mobility shift assay with 32P-labeled oligonucleotide probes, we detected HeLa cell nuclear as well as cytoplasmic factors that bind to MRE sequences of human MTIIA (hMTIIA) gene. One of the nuclear factors, which gives stronger signal than others, was further characterized. Competition experiments showed that the nuclear factor (named MREBP) specifically recognizes MREs of hMTIIA gene. EDTA abolished the binding of MREBP to MRE, suggesting that a divalent cation(s) is required for the complex formation. Also in blotting experiments with HeLa nuclear extract and the [32P]MRE probes an EDTA-sensitive 95k protein band, which possibly represents MREBP, was detected.

Base Sequence↗